Pop-up notifications

[Slaught]

I have two notifications pop up when there should only be one (basically, just doubling the notifications) and I want to prevent that.
Also, how do you toggle how long the notification stays on your screen?

[quietbritishjim]

Go into preferences. On the events page go onto the advanced tab, and if there are duplicate contact signon/off events (near the top) delete them.

I don't there is such an option I'm afraid, except that on the events page I've just told you about you can make them persistent i.e. they never go away, unless you click on them (right click dismisses them without opening a message window).